unless they have figured out how to randomly generate textures without a pattern,then this is absolutely overlay.
I sure see the patterns (have to be quick and/or slow the video down and pause it throughout the video)
Should there be perfect fairway mow lines on the green at 17? (asking)
It doesn't really look like the crosshatch one might expect (and sees in some real life photos) -- looks more like the general TGC mow lines that are all over their courses.
Thankfully they are toned down (this is what creates some of the Mario Golf effect they had issues with in the past)